• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.365-376
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• 2007

The purpose of this study was to evaluate the effect of different etching times on microtensile bond strength (${\mu}TBS$) to dentin both initial and after thermocycling with 3 different types of total-etching adhesives. Fifty four teeth were divided into 18 groups by etching times (5, 15, 25 sec), adhesives types (Scotchbond Multipurpose (SM), Single Bond (SB), One-Step (OS)) and number of thermocycling (0, 2,000 cycles). Flat dentin surfaces were prepared on mid-coronal dentin of extracted third molars. After exposed fresh dentin surfaces were polished with 600-grit SiC papers, each specimen was acid-etched with 35% phosphoric acid (5, 15, 25 sec) and bonded with 3 different types of total etching adhesives respectively. Then, hybrid composite Z-250 was built up. Half of them were not thermocycled (control group) and the ethers were subjected to 2,000 thermocycle (experimental group). They were sectioned occluso-gingivally into $1.0\;{\times}\;1.0\;mm^2$ composite-dentin beams and tested with universal testing machine at a crosshead speed of 1.0 mm/min. Within limited data of this study, the results were as follows 1. There was no statistically significant difference in ${\mu}TBS$ between the thermocycled and non-thermocycled groups, except for both SM and SB etched for 25 sec. 2. In thermocycled SM and SB groups, bond strength decreased by extended etching time. In total etching systems, adhesive durability for dentin could be affected by type of solvents in adhesive and etching time. Especially, extended etching time may cause deteriorate effects on bond strength when ethanol-based adhesive was used.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.1
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• pp.1-8
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• 2023

Purpose: The purpose of this study is to analyze the prognostic factors related to tooth loss after 5 years of periodontal surgery in periodontal disease patients. Materials and Methods: From January to December 2017, 22 patients and 124 teeth who underwent periodontal treatment through periodontal surgery were targeted. At the time of treatment, the measured values were evaluated after recording the maximum probing depth, average periodontal probing depth, number of root, furcation involvement, pulp vitality, and prosthesis state on the day of periodontal surgery. Based on the initial records at the time of visit, patient-related factors were gender, age, smoking, tooth loss due to periodontal disease at the time of first visit, diabetes, and maintenance period. The influence of each factor on tooth loss was evaluated. Results: As a result of examining the influence of tooth-related factors on tooth loss, the maximum probing depth depth (P: 0.000), bone loss (P: 0.021) was found to have a significant effect on tooth loss. Conclusion: As a result of examining the influence of patient-related factors on tooth loss, any variables had no significant effect. Bone loss, maximum probing depth acted as statistically significant prognostic factors for tooth loss in patients who underwent periodontal surgery.

• The korean journal of orthodontics
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• v.36 no.1 s.114
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• pp.45-54
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• 2006

Recent beauty trends have caused an increase in the number of bialveolar protrusion patients seeking treatment of lip protrusion. But studies of these patients are not common. Studies using their dental models are especially rare. Dental models have been measured manually or through a computer by digitizing two dimensional images of models. Nowadays, we are able to study dental models more easily and accurately by utilizing the three-dimensional (3-D) laser scanner in dentistry. An investigation was carried out to evaluate the characteristics of the dental arch in a bialveolar protrusion group in comparison with a normal group using 3-D digital models. The normal group was composed of 20 subjects who were selected from students of the School of Dentistry, Kyungpook National University. The bialveolar protrusion group was composed of 20 subjects who visited for treatment at the Department of Orthodontics, Kyungpook National University Hospital. Tooth size, arch width and arch length were measured digitally, and arch shape and the shape of the palate were drawn. Based on the results of this study, the differences of the arch characteristics in the bialveolar protrusion group were that the size of the teeth was larger, mandibular canine width and 1st premolar width were wider, and arch length was longer than in the normal group. And there were differences in the arch shape and the shape of palate between the bialveolar protrusion and normal groups.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.3
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• pp.243-249
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• 2018

Excessive tooth wear results in unacceptable damage to the occlusal surface and can cause pulpitis, occlusal disharmony, dysfunction, and unesthetic result. Patients with severe attrition have to be classified as several types relative to the vertical dimension of occlusion (VDO) and the interocclusal distance for the prosthetic space. The patient in this case was a 80 - year - old woman who lost support of posterior occlusion and collapsed of the occlusal plane due to confrontation of the opposing teeth, accompanied by an increase in the number of remaining bristles, resulting in a loss of intermaxillary space for prosthesis. In this case, treatment with increased vertical dimension may have stability if the increase in vertical occlusal height is minimized within the required range, and a stable occlusal contact is provided after an increased vertical occlusal height stabilization period. After the new VDO had been confirmed under interim fixed restorations, definitive fixed restorations were produced. Through these treatment processes, we obtain satisfactory results that are functional and aesthetically pleasing.

• Journal of dental hygiene science
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• v.5 no.2
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• pp.89-95
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• 2005

Dental caries is the most prevalent dental issue of childhood. So it is important to control caries form 5 years children and above all, the study of oral health status have been preceding for preventive dental caries. The purpose of this study was to assess the oral health status of 5 years children in seongnam city. The study population consisted of 1035 kindergraten children which had been selected stratified random sampling. The survey is based on WHO, 2000 oral health assessment, which has been modified. From data dt index, ft index, dft index, dt rate, ft rate, percentage of active caries, percentage of pit and fissure sealant, and so on. The findings were as follows: (1) In 5 years children, the experience of dental caries was 73.0% and the percentage with active caries was 49.4%. Dmf index was 4.13 and this observation shows a statistical singnificance. (2) Average number of 5 years children the experience of dental caries surface index was 3.11 and dfts index was 8.91. (3) The experience of dental caries fo the frist molar was 1.9% and the percentage with active caries was 1.1%. Otherwise the percentage of pit and fissure sealant of the first molar was 6.7%. It is show the low percentage for preventive dental caries. (4) Shows percentage of teeth needing treatment for one surface and above two surface was each 27.3%, 34.0%. And percentage of children required single crown and pulp treatment & single crown and tooth extraction was each 3.8%, 4.7%, 3.3%. (5) Soojung-gu and jungwon-gu were having poor oral hygiene as compared to bundang-gu. So it is necessary to establish community oral health program effectively. And for preventive dental caries and early diagnosis and early treatment consider with community characteristic.

• Journal of Korean society of Dental Hygiene
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• v.7 no.2
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• pp.177-187
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• 2007

The purpose of this study was to examine whether dating affected young people's concern for their looks and their oral health state, and to motivate students to promote their oral health, as national oral health depended on students who would grow into eligible members of society in the near future. Relevant literature and data were reviewed, and a survey was conducted on residents in and around Seoul, who were in their 20s, for approximately three months from June through August 2006 to find out about their oral health status. The findings of the study were as follows: 1. Whether they were seeing someone or not was investigated, and it's found that 37.5 percent had a girl friend or boy friend, and that 6.7 percent hadn't. 2. Concerning the state of dating, 40.3 percent, the largest percentage, had been dating for less than a year, and the largest number of them that accounted for 23.6 percent had been dating one person till then, 4.0 percent were considering getting married with those whom they were seeing. The most dominant type of love was eros(romantic or ardent love; 41.7%), followed by stroge(friendly love; 33.3%), and agape(altruistic, devoted love; 12.5%). 3. As for the impact of dating on oral health status, those who were seeing someone were similar to those who weren't in toothbrushing frequency, toothbrushing time and simplified oral hygiene index. There was no significant gap between the two. 4. Concerning the influence of dating on dental-treatment experience, no statistically significant intergroup differences were found in experiences of taking dental-caries treatment, bad-breath treatment and teeth-whitening treatment. There was a statistically significant intergroup gap only in scaling experience(pE0.05). 5. Regarding the impact of dating on oral health care, 59.7 percent of those who were dating thought that it affected oral health care, and the same rate of the others who weren't stood at 38.3 percent. There was a statistically significant gap between the two(pE0.01). 6. As to the influence of general characteristics on oral hygiene index, their age and gender made no statistically significant differences to that. By occupation, however, many of the company employees were in good oral health, and many of them were in bad oral health, too. The office workers were statistically significantly different from the others in that regard(pE0.01).

• Journal of Biosystems Engineering
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• v.3 no.1
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• pp.20-36
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• 1978

The effect of binder kicking forces on the shattering losses of paddy rice, which has been widely understood as an outstanding loss factor in harvesting with a binder, were experimentally assessed in this thesis.Through the field tests the optimum time of harvest, in terms of grain moisture contents, was found by considering harvesting losses for two rice varieties, harvested by two different binders, at four or five grain moisture levels.A device was designed and manufactured to apply various kicking forces to the bundles and was used in the bundle kicking tests. It was intended to find out the optimum range of kicking force to minimize the kicking losses. Based on the study, modification of the existing binder kicking mechanism was suggested. The following is a summary of the results of this thesis. 1. In Suweon 258 variety, as the grain moisture content is reduced, so the cutting loss and the kicking loss increase. The grain losses range from 0.77 to 0.82 percent of total field yield for the cutting loss, from 1.83 to 2.01 percent for the kicking loss, and from 2.60 to 2.83 percent for the field loss, when the moisture content is about 22 percent. 2. In Jinheung variety , the field losses increased as the grain moisture content decreased . When the moisture content was 20 percent, the field loss, cutting loss and kicking loss was 0.42-0.49 % , 0.30-0.35, and 0.12 -0.14% of the total field yield, respectively. 3. The difference in the field loss , cutting loss, and kicking loss for the two binders was 0.23% , 0.05% and 0.18% respectively in Suweon 258 variety, and 0.07% , 0.02% and 0.05% respectively ini Jinheung variety. The grain losses for binder B were slightly higher than those for binder A. 4. In the statistical analysis of each variety , the kicking force and the moisture content of the grain, and its interaction were all highly significant at 1% level by T test .The optimum kicking force was found to be in the 3.0-0.4kg range. This does not interrupt the binder operation, while ioses are kept to an acceptale level. 5. To reduce the kicking force of the eXlstmg binder mechanism, the speed of rotation of the kicking arm needs to be redued by increasing the number of driving sprocket teeth, and the position and gear ratio of the knotter-bill and driving bevelgear have to be change to give a !motter-bill speed of 1110 rpm. It is also desirable to attach a belt conveyor which smoothly carries the bundle to the ground. 6. The optimum harvesting time cased on maximum field yield was found to be at a grain moisture content of around 22 percent for Suweon 258 variety, and 20 percent for Jinheung variety. Tota] field yield and field yield at the time amounted to 9, 812.5 kg/ha, 9, 302. 5kg/ha respectively for the Suweon 258, and 7, 819.5 kg/ ha, 7, 158.7 kg/ha respectively for the Jinheung variety.

• Journal of Korean Academy of Oral Health
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• v.41 no.4
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• pp.243-249
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• 2017

Objectives: Stress is a psychological reaction to stimuli such as anxiety or threat felt by a person either physically or mentally when placed in a difficult situation. Although a relationship between stress and dry mouth has been reported, it remains understudied. The purpose of this study was to investigate the association between stress and subjective dry mouth among the elderly living in a rural region. Methods: A total of 214 people aged ${\geq}60years$ living in a rural area were recruited with an informed consent for a cross-sectional analysis. Information about stress and subjective dry mouth was obtained by an interview survey with a constructed questionnaire. Data on other potential confounding factors (including oral factors) such as socio-demographic data, health-related behaviors, the number of remaining teeth, and subjective chewing ability were also gathered at the same time. Logistic regression models were used to analyze the relationship of stress and dry mouth using SPSS. Results: The Crude odds ratio (OR) of stress awareness affecting subjective dry mouth was 2.59 (95% confidence interval: 1.43-4.68). After adjusting for sex, education, income, smoking, and alcohol intake, the adjusted OR was 2.52 (95% confidence interval: 1.30-4.87) which was statistically significant. Conclusions: Elderly people who were stressed had an approximately 2-fold increase in experiencing subjective dry mouth when compared to their stress-free counterparts.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.4
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• pp.412-418
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• 2017

During orthodontic treatment, formation of white spot lesions (WSLs) around brackets has long been recognized as a potential risk. This study performed to investigate effect of preventing enamel demineralization and remineralization by application of fluoride-containing orthodontic primer. Fifty extracted bovine incisors teeth were randomly allocated to 3 groups: (I) Non-preparation specimens, (II) Application of Light Bond$^{TM}$ as fluoride containing orthodontic primer, (III) Application of Transbond$^{TM}$ XT Primer as traditional orthodontic primer without fluoride. Each group is demineralized under artificial carious solution. The demineralization pattern was evaluated using a Q-ray view, Vickers hardness test and polarized light microscope. The remained primer was calculated as 35 - 50%. The highest surface microhardness was shown on Light Bond$^{TM}$ surface. There were statistically significant differences in Vickers microhardness number between adjacent areas of Light Bond$^{TM}$ and non-prepared area. There was almost no demineralization of the enamel surface under the Light Bond$^{TM}$. At the adjacent site of Light Bond$^{TM}$, the shallow caries pattern and remineralization appearance were also observed. These results suggest that the use of fluoride-containing primers may be useful for bracket attachment to reduce enamel demineralization during orthodontic treatment.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.179-185
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• 2010

Molar Incisor Hypomineralization(MIH) have recently gained intensive research interests and various clinical trials. Most prevalence, etiology, treatment studies in MIH were carried out in the European countries, and data from the Korean were seldom. This study aimed to investigate the prevalence of MIH and the status of dental caries and treatment on the first permanent molars in primary school children. For this study, 1,344 primary school students in Busan and Ulsan cities were examined directly the permanent incisors and first molars. The results of the survey were as follows: 81 MIH cases were identified among 1,344 cases. The prevalence of MIH in this group of children was 6.0%. Children with MIH showed a significantly higher DMFT value for permanent teeth than children without MIH. The mean number of decayed, missed, and filled in 1st permanent molars(DMFT index) was 1.17. The rate of children with restoration on 1st permanent molar was 13.6% and the sequence of restoration materials was as follows : composite resin, amalgam, gold inlay.